The present invention relates to telecommunication systems. The invention concerns a method and system for redefining the configuration of an interface between two network elements.
Two network elements, such as an access node and a local exchange, can be connected to each other using e.g. the V5.1 or V5.2 protocol. Open interfaces (V5.1 and V5.2) between an access node and a telephone exchange are defined in the ETSI (European Telecommunications and Standards Institute) standards. V5 interfaces enable subscribers belonging to a physically separate access network, which may be a wired or a wireless network, to be connected using the standard interface of the telephone exchange. A dynamic concentrator interface 5.2 consists of one or more (1-16) PCM (Pulse Code Modulation) lines. One PCM line comprises 32 channels or time slots, each of which has a transfer rate of 64 kbit/s, so the total capacity of the PCM line is 2048 kbit/s. The V5.2 interface supports analog telephones as used in the public telephone network, digital, such as ISDN (Integrated Services Digital Network) basic rate and primary rate interfaces as well as other analog or digital terminal equipment based on semi-fixed circuits.
The standards concerning the V5 interface define two different ways of changing the specifications of a V5 interface already in operation. Changing the specifications means e.g. removing a signalling channel to a different time slot or adding new signalling channels. Such changes can be made by using the so-called reprovision function defined in the standard, whereby the changed specifications are given a new xe2x80x9cdesignationxe2x80x9d (provisioning variant) in both network elements, i.e. in the local exchange and the access node, and a check is carried out to make sure that both parties are ready for the change. The provisioning variant is a parameter which is checked in conjunction with the start-up of the V5 interface. This parameter is given numeric values corresponding to certain predetermined configurations of the V5 interface. However, changes can be made in the V5 interface even without using the reprovision function. In this case, the changes are made independently at both ends without changing the value of the provisioning variant parameter. When the changes are activated, the changes specified are made automatically at both ends and the interface is started up.
The configuration of a V5 interface connecting two network elements can be changed as necessary, e.g. by introducing new links or signalling channels. The network elements verify their readiness for the change of configuration by exchanging messages. Before a change can be made, all subscriber ports in the interface have to be blocked. A new signalling channel can not be introduced if the corresponding time slot is occupied by an active connection, e.g. a call going on.
In prior-art technology, e.g. as defined in the ETS 300 342-1 standard, February 1994, section 7.2.2., when the configuration is to be changed, the subscriber ports are blocked without disturbing connections that are currently active or in the process of being established. Free subscriber ports are blocked immediately, and busy ports upon termination of the calls. The blocked subscriber ports cannot set up any connections before the blockage has been removed.
The problem in the above-described situation is that even a single connection of long duration, such as an Internet connection, may occasion a long break in telephone communication for a large number of subscribers.
The object of the present invention is to eliminate the problem referred to above or at least to significantly alleviate it. A further object of the invention is to disclose a new type of method and system that will allow the configuration of an interface between network elements to be redefined without causing major difficulties to any particular subscriber group.
The invention concerns a method for redefining the configuration of an interface in a telecommunication system comprising a first and a second network element, subscriber ports comprised in the network elements and an interface connecting the subscriber ports of the first and the second network elements to each other. The interface is preferably a V5 interface. In the method, free subscriber ports are blocked and the configuration of the interface is redefined after all subscriber ports have been blocked. According to the invention, a connection established or being established by a subscriber port is disconnected, thus releasing the subscriber port. The released subscriber ports can then be blocked immediately.
In an embodiment, the connection of a subscriber port is disconnected after the lapse of a predetermined length of time. In this case, it is possible to define a kind of buffer time, in the course of which a suitable proportion of the subscribers are likely to terminate their connections. Within the buffer time, for those subscribers who have no active connection or who break a connection during it, the subscriber port can be blocked. Thus, blocking the subscriber ports will only produce a disturbance for those subscribers who are having a connection of a duration longer than the specified buffer time or who try to set up a new connection during the buffer time.
In an embodiment of the method, to reconfigure the interface, the provisioning variant parameter for the interface defined in the V5 specifications is modified. Provisioning variant is one of the parameters that are verified in conjunction with the startup of the V5 interface. This verification is carried out to make sure that the local exchange and the access node observe the same configuration in the V5 interface. Configuration refers in the first place to the position and order of the signalling channels. When the parameter is given a new value, this means that e.g. the signalling channels use another time slot. Before the changes are activated at both ends, i.e. before the interface is started up, the appropriate devices first check via signalling that the new value of the provisioning variant parameter is known at both ends, whereupon the configuration changes required by this parameter are made independently.
The invention also concerns a system for redefinition of the configuration of an interface in a telecommunication system as described above. The system of the invention comprises means for disconnecting an existing connection or a connection being established via a subscriber port before blocking the port. In an embodiment of the invention, the system comprises means for disconnecting the connection of a subscriber port after the lapse of a predetermined length of time. The interface is preferably a V5 interface. In an embodiment, the system comprises means for redefining the configuration of the interface by modifying the provisioning variant parameter for the V5 interface defined in the V5 specifications.
The invention provides the advantage of minimizing the time consumed in effecting a configuration change. Normal telephone traffic is made possible for all subscribers without any long waiting times. Thus, the service received by subscribers connected to an access node via a concentrating link is improved. In practice, this means that, in conditions of crisis and similar circumstances when it is absolutely necessary to be able to set up a call, the probability of successful setup of a priority call can be improved. In addition, the invention is applicable to both terminating and outgoing calls and is therefore very useful.
The invention is also particularly useful when both the local exchange and the access node consist of equipment manufactured by the applicant, e.g. when the local exchange is a DX200 switching center and the access node is a DAXnode5000.